gen.subproj/getnetent.3

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  32 .\"     @(#)getnetent.3 8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/net/getnetent.3,v 1.11.2.3 2001/08/17 15:42:38 ru Exp $
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  35 .Dd June 4, 1993
  36 .Dt GETNETENT 3
  37 .Os
  38 .Sh NAME
  39 .Nm getnetent ,
  40 .Nm getnetbyaddr ,
  41 .Nm getnetbyname ,
  42 .Nm setnetent ,
  43 .Nm endnetent
  44 .Nd get network entry
  45 .Sh LIBRARY
  46 .Lb libc
  47 .Sh SYNOPSIS
  48 .Fd #include <netdb.h>
  49 .Ft struct netent *
  50 .Fn getnetent void
  51 .Ft struct netent *
  52 .Fn getnetbyname "const char *name"
  53 .Ft struct netent *
  54 .Fn getnetbyaddr "uint32_t net" "int type"
  55 .Ft void
  56 .Fn setnetent "int stayopen"
  57 .Ft void
  58 .Fn endnetent void
  59 .Sh DESCRIPTION
  60 The
  61 .Fn getnetent ,
  62 .Fn getnetbyname ,
  63 and
  64 .Fn getnetbyaddr
  65 functions
  66 each return a pointer to an object with the
  67 following structure
  68 containing the broken-out
  69 fields of a line in the network data base,
  70 .Pa /etc/networks .
  71 .Bd -literal -offset indent
  72 struct  netent {
  73         char            *n_name;        /* official name of net */
  74         char            **n_aliases;    /* alias list */
  75         int             n_addrtype;     /* net number type */
  76         unsigned long   n_net;          /* net number */
  77 };
  78 .Ed
  79 .Pp
  80 The members of this structure are:
  81 .Bl -tag -width n_addrtype
  82 .It Fa n_name
  83 The official name of the network.
  84 .It Fa n_aliases
  85 A zero terminated list of alternate names for the network.
  86 .It Fa n_addrtype
  87 The type of the network number returned; currently only AF_INET.
  88 .It Fa n_net
  89 The network number.  Network numbers are returned in machine byte
  90 order.
  91 .El
  92 .Pp
  93 The
  94 .Fn getnetent
  95 function
  96 reads the next line of the file, opening the file if necessary.
  97 .Pp
  98 The
  99 .Fn setnetent
 100 function
 101 opens and rewinds the file.  If the
 102 .Fa stayopen
 103 flag is non-zero,
 104 the net data base will not be closed after each call to
 105 .Fn getnetbyname
 106 or
 107 .Fn getnetbyaddr .
 108 .Pp
 109 The
 110 .Fn endnetent
 111 function
 112 closes the file.
 113 .Pp
 114 The
 115 .Fn getnetbyname
 116 function
 117 and
 118 .Fn getnetbyaddr
 119 sequentially search from the beginning
 120 of the file until a matching
 121 net name or
 122 net address and type is found,
 123 or until
 124 .Dv EOF
 125 is encountered.
 126 The
 127 .Fa type
 128 must be
 129 .Dv AF_INET .
 130 Network numbers are supplied in host order.
 131 .Sh FILES
 132 .Bl -tag -width /etc/networks -compact
 133 .It Pa /etc/networks
 134 .El
 135 .Sh DIAGNOSTICS
 136 Null pointer
 137 (0) returned on
 138 .Dv EOF
 139 or error.
 140 .Sh SEE ALSO
 141 .Xr networks 5
 142 .Pp
 143 .%T RFC 1101
 144 .Sh HISTORY
 145 The
 146 .Fn getnetent ,
 147 .Fn getnetbyaddr ,
 148 .Fn getnetbyname ,
 149 .Fn setnetent ,
 150 and
 151 .Fn endnetent
 152 functions appeared in
 153 .Bx 4.2 .
 154 .Sh BUGS
 155 The data space used by
 156 these functions is static; if future use requires the data, it should be
 157 copied before any subsequent calls to these functions overwrite it.
 158 Only Internet network
 159 numbers are currently understood.
 160 Expecting network numbers to fit
 161 in no more than 32 bits is probably
 162 naive.